Phase diagrams | States of matter and intermolecular forces | Chemistry | Khan Academy

[@parttimeconstruction2933]

this mans voice brings me comfort knowing that he will actually teach me unlike my chem professor

[@gdullard]

how the hell does this guy know everything. He covers so many university topics. such a capacity to learn!

[@eshalshoaib5923]

​@amateur_01💀

[@Ilikesoda100]

Reverse sublimation is deposition just in case you needed to know

[@anavillacreses4112]

aka gas --> solid

[@parshgoel950]

@@JAYWLEE Bruh

[@addy7464]

Thanks

[@stephaniem9769]

I wish Sal was my teacher in all science subjects ever

[@spaff61]

i love watching these videos, they have helped me understand a lot with my electrical course i am doing. thank you for taking the time to post these Khan

[@wbhowden]

It is dependant on the beginning temperature of the solid, the final temperature of the gas and the substance in question. For 1g of water, from 0*C solid to 100*C gas: Hf: 333.55 J/g Hv: 2257 J/g Specific heat of liquid water: 5.178*C Therefore: (5.178 J/g x 1g x 100*C) + 333.55 J/g + 2257 J/g =7769 Joules to heat 1g of water from 0*C solid to 100*C gas

[@prakashzala1840]

Sal , i really respect you .. u r the best teacher. I wish u take my all subjects.

[@samanvayabhi9541]

mind blowing explanation , after watching sir my whole mind start blowing mean while concept clear thanks

[@khanacademy]

yes, that is correct

[@phookadude]

Water ice does sublimate at freezing. If you leave a tray of ice cubes in your freezer for a long time they will shrink. This is also how freeze drying works, you freeze something at low pressure and the water sublimates out.

[@mrcoatsworth429]

Great video. Thanks!

[@Von-dee]

Life saver, ALWAYS! Since high school and now university.

[@someonecalledjoshua2612]

I'd like to point out that water is a peculiar fluid. Normally, the melting point of a substance would increase when pressure increases. This is due to water ice's special structure. But still, great video!

[@Chanikachang]

You are an amazing teacher!! Thank you so much! Been trying to read and understand this stuff for two days now and I watch one of your videos and Boom! I got it...Just want to say THANKS!!! =D

[@Ahmedrob1]

that tremendous :) thanks so much !

[@curtpiazza1688]

I finally understand phase diagrams! 😊🎉

[@scottseptember1992]

At the moment liquid water at 0 degrees Celsius changes to solid water/ice at 0 degrees Celsius (thus a phase change), I understand there is no change in kinetic energy/heat because that energy is being used to break the intermolecular forces/H-forces between the water molecules.

[@markkeith9055]

This was so helpful. Thank you.

[@nomeepatel2411]

Students like us need teacher like u👍

[@merlin8273]

12:20 it’s deposition

[@JAYWLEE]

reverse sublimation is the same thing as deposition

[@08060915]

This makes things easier : )

[@MrAlb0t]

@khanacademy you have no idea how helpfull you were :) thanks !

[@ultimatehemang]

amazing video....sir....you just make the concept...so simple..i hate sitting in any lecture....your videos keep attracting me....thank you sir

[@mohamedelyas9294]

Great illustration, thanks alot.

[@swarnavasaha4079]

The explanation was so easy to understand. Thank you so much.

[@fogofchess]

@pog21 it's counterintuitive, but makes sense because ice is less dense than water

[@emmanuelagwu6730]

God bless you immensely sir 😊

[@Emmaredman440]

thanks so much this helped me so much for my science competition

[@MsChaChingChaChing]

why is it that given a constant temperature, a solid becomes liquid? shouldnt it be the other way? wouldn't the increased pressure force the molecules to stick closer together? in addition, at a low temperature, a gas can directly become a solid without going through the liquid stage? this is what the diagram shows. thanks

[@Ameelz]

I needed this. what with the chemistry test tomorrow

[@TheJoshtheboss]

So why does solid-->liquid require higher temperature at lower pressure? I understood the concept for liquid-->gas that lower pressure essential reduces the resistance for water molecules to escape.

[@MrAlb0t]

@Metropolitianif im not wrong :p(and please correct me if i am), dQ = mc where m is mass and c its the latency heat (or whatever its called in english) that varys from compound to compound and the states you are going from and to. hope i helped a bit :)

[@danielwhitwell1967]

Great explanation. Makes so much more sense now.

[@moscovman232]

The word for reverse sublimation is deposition. Thanks for the video, It was very helpful.

[@masterdenz91]

Now i'm thinking: a gass giant is big so it has a lot of gravity therefore high pressure and since its a gass giant it must be close to a star to gain enough heat to maintain a gass phase. Or is it just because of the certain elements that the gass giant contains that it can remain in a gass phase. I would like to hear an answer from someone who knows how this works. Thanks btw for another great video!

[@virupannamedikinal]

Thank you so much Sir

[@lookaway8496]

can you explain about the assumptions you made about Denver and Death Valley? saying that freezing point is low in Denver?

[@PigsCanFly99]

phase bndry btwn liq and sol is near vertical for H20. M.P. depression through pressure is minimal. Skating is NOT due to pressure-induced melting of ice .. complete bunkum. Read up on "theory of skating is "all wet"

[@MattieMattieMattiful]

Excellent video, as usual, but I am assuming that Sal had too much in his brain at the end of the video to remember that deposition is the opposite of sublimation? He mentioned condensation, while he was trying to remember, which is molecules going from a gas to a liquid; but, going from a gas to a solid is deposition (e.g., water vapor on a cold window forming ice crystals). The opposite, of which, is sublimation: going from a solid to a gas (e.g., "dry ice").

[@Ddayghost]

Made it simple. Thank you so much sir.

[@kickflip97]

You are my chemistry jesus without you I would be studying the wrong way for my final. Thank you so so much!

[@andrewlau7521]

How did the final go

[@ricefarmer42069]

@@andrewlau7521 he failed

[@Tasniaaaaaaaa]

I love how your videos are helpful for people of all levels, whether its a regular level high school class or an AP or college level class. You make learning chemistry so much less dreadful!!!

[@Tasniaaaaaaaa]

@amateur_01 LOL yes I am alive and well. I’m almost a doctor and Khan really helped with that.

[@sciencenerd7639]

thank you

[@farjanajamal8802]

A lot of love and respect , you are an excellent teacher

[@5185988519]

Thank you so much. I guess I'm like the fifty millionth person to say this, but this was awfully helpful. What program did you use to show this?

[@justinballew]

Adderall and Khan go together well. Especially before finals.

[@markkraman886]

Top mentor, globally.

[@MsChaChingChaChing]

@MsChaChingChaChing how do we explain given a certain temperature if we start out as a gas and we increase the temperature, it becomes a solid and if you further increase the temperature, it becomes a liquid again? i dont understand this. in addition, is there a critical point where the temperature and pressure are so low, it is hard to distinguish between a solid and a gas? same for solid and liquid?

[@Lorcan.oshanahan]

the word you were looking for is Deposition. i think is so you should add it as an annotation. :)

[@mattk.8637]

Awesome video! I believe deposition is reverse sublimation.

[@chandrakommanapotluri7306]

Thank you so very much.

[@mirhebibseydeliyev1230]

thanks for such a good video. that helped me to understand very well.

[@sattamdatta8921]

Thank u so much, excellent helpful video

[@scottseptember1992]

However, I don't understand why the "potential energy" would decrease during this phase change from liquid to ice/solid water because, since ice is less dense than either of it's previous forms, the distance between the H2O water molecules will be greater thus an INCREASE in potential energy (because H2O forms a net like structure in it's solid state). Any suggestions?

[@endaputri4085]

Hello.. Nice to meet your account and I am totally subscribed bte... So Idk why but with you told me all this stuff i understand it.. 😁.. Tomorrow maybe I'll presentation this on class.. So.. Thank you.. Such a great skill there.. 😁.. Anyway you're so funny so i enjoyed your explainations.. Although I am second this language.. So... Great.. 😁

[@sigmoidsharer3012]

thanks

[@considerthis215]

i think its because water expands as it cools down

[@YUMiiEEx]

you are so great! thanks for uploading this! you teach very well and i like your references/examples :D

[@crumcon]

why are you so smart???? i wish i was you! :)) thx for the wonderful explanation

[@Kartikeyasain]

IS IT POSSIBLE TO CONVERT ANY LIQUID INTO GAS KEEPING TEMPERATURE CONSTANT AND PRESSURE AND VOLUME CAN VARY?

[@LOOL134]

giggled when you were thinking of the word. thank you! great vid

[@mateodhowe6085]

yo what

[@bta1987]

what you said is only true for the water phase diagram at region below zero degree C. Phase diagrams for ALL other substances besides water are different (the solid/liquid line "tilt" to the right instead of the left as in water) Since ice is "less dense" than liquid water (h2o molecules "spaced" out more in ice), increasing the pressure means "squeezing" those h2o shits closer together & thus they turn into liquid water (which is "more dense" than ice because h2o molecules "spaced" out less)

[@mishkaismail8687]

Thank you! =)

[@UncertainHeisenberg1]

In this case Hess' Law is applicable. You simply sum the heats of fusion and vaporization.

[@nisnber5760]

How cool would it be to get H2O from a gas, to a solid and then to a liquid as you raise atmospheric pressure while keeping the temperature constant!

[@Upgradezz]

Oh, Thank you!

[@thezootcat4271]

thank you so much besto friendo

[@cicco6211]

I have a question, the pressure that i use as variable in the axis, is that the pressure of the atmosphere, actually the external pressure; or is that the vapour pressure of the compound? For example the vapour pressure of water?

[@waleedaltaf5852]

The pressue given on the y axis is the atmospheric pressure not the internal vapour pressure.

[@gudiyappac7030]

Flavio Sabatelli g

[@LaraZ0]

If anyone is watching through the videos, could they please reply to this comment all of the annotations/mistakes that Sal made (up to Van Der Waals Forces, video 30)? By this, I mean all the bubbles that popped up when he corrected himself. I'm afraid I missed some since I watched mostly on my phone, and I don't want to have learned wrong information. Thank you!

[@Hunter0fSouls]

polar bonds used instead of hydrogen bonds

[@bengrove7929]

It depends on the substance.

[@nhu4459]

So how do we find the difference of the melting and freezing point of a substance at STP?

[@waleedaltaf5852]

Liquids have a characteristic temperature at which they turn into solids, known as their freezing point. The melting point of a solid should be the same as the freezing point of the liquid. In practice, small differences between these quantities can be observed at stp.

[@cuneytyldz5326]

nh3/n2h4 how can i reach the phase diagram

[@Seranguyen]

I am having a hard time imagining H2O at equilibrium. Does anyone have any image or visual aid? Thank you.

[@ericpham9106]

How can you use atomic theory to explain ice lower density compare to water. And that where the periodic table failed

[@navyav8]

what's with the interruptions?

[@JAYWLEE]

what would be an ideal score of a freshman taking the sat chemistry test?

[@lbabycutiec]

ohmygosh, I love you.

[@sd753]

Having finals in 2 hours!!!

[@AAA-vf2qr]

Somewhat late, but how'd you do?

[@CeruleanDreamer]

@@AAA-vf2qr somewhat? 😂😂

[@ERboss-87]

just a lil late but we all want to know mate, how did it go???

[@jay.jay.]

@@ERboss-87 he probably forgot himself. It's been 7 years lol. But I would also like to know how did it go

[@JamesVestal-dz5qm]

Sublimation doesn't depend on what planets surface you stand.

[@srbirajdar]

Heat of Sublimation...

[@rekhraj7]

this is good stuff.... damn my chemistry teacher sucks...lol...thank you! :D

[@rekhraj7]

@crackhead1492 i think the main idea to convey is that water take less time to boil in everest due to pressure difference...and not by how will the water be boiled.... electric can also be applied to boil water and not only fire :)

[@thoraxepi]

In my book there looks like there's a little "bump" near the triple point. Why is that?

[@RomeroGrinerdam]

So, in deep sea waters (high pressure and almost 0ºC) we may have liquid CO2? If I remember well, sublimation is the word used for both sides of the same process.

[@williamhewitt4748]

Deposition is the word you were looking for

[@mahmoudashraf117]

deposition is inverse sublimation :)

[@mikeman473]

@MintiMissa love the mountains there

[@markkeith9055]

Didn't they have that blue ice stuff for keeping coolers cool? That was frozen CO2, right?

[@shahindagaber2983]

الكلمة تبقى deposition 😂😎😎💙

[@sydneyresnick1176]

Good video! The word is deposition hahah

[@XOXLIVETOLOVE]

Haha the liquid molecules are touching e/o and rubbing up against e/o. lmao loved the vid

[@prabhanshukatiyar4635]

whats is his favorite color?

[@AneeseJemarcus]

A lot of chemists just use the word sublimation rather than deposition, and you can just understand weather it means going from solid to gas or from gas to solid from the context.

[@Born_to_be_an_Officer]

Here because, day after tomorrow is my collg exam 😨😖

[@sastido]

deposition!

[@saviosflaw]

Phaaaaaaaaaase Diagram!

[@JamesVestal-dz5qm]

My students thought dry ice was dumb.

[@sciencenerd7639]

Deposition. Deposit that in your brain.

[@sameenaz2006]

Its DEPOSITION that you are looking for SAL. :]

[@pepegpala]

i love you